Thursday, October 22, 2015

"The recent extended, deep minimum of solar variability and the extended minima in the 19th and 20th centuries (1810–1830 and 1900–1920) are consistent with minima of the Centennial Gleissberg Cycle (CGC), a 90–100 year variation of the amplitude of the 11-year sunspot cycle observed on the Sun and at the Earth. The Earth’s climate response to these prolonged low solar radiation inputs involves heat transfer to the deep ocean causing atime lag longer than a decade."

The authors find,

"The spatial pattern of the climate response [to the Gleissberg solar activity cycle]... is dominated by the Pacific North American pattern (PNA). The Gleissberg minima, sometimes coincidently in combination with volcanic forcing, are associated with severe weather extremes. Thus the 19th century Gleissberg minimum, which coexisted with volcanic eruptions, led to especially cold conditions in United States, Canada and Western Europe."

The paper shows clear evidence in the first graph below of a significant, sustained increase of Total Solar Irradiance (TSI) from 1700 to the late 20th century, coincident with the end of the Little Ice Age ~1850 and the global warming observed during the 20th century. The paper is coauthored by Joan Feynman (sister of the famous physicist Richard Feynman).

Total Solar Irradiance in top graph shows a significant increase of solar activity since 1700. Second wavelet graph shows periodicity (red areas) corresponding to the 90-100 year Gleissberg cycle of solar activity. Bottom graph shows smoothed Gleissberg cycles since 1700.

Second graph solid line shows Total Solar Irradiance correlates with observed land temperatures (dashed line).

The recent extended, deep minimum of solar variability and the extended minima in the 19th and 20th centuries (1810–1830 and 1900–1920) are consistent with minima of the Centennial Gleissberg Cycle (CGC), a 90–100 year variation of the amplitude of the 11-year sunspot cycle observed on the Sun and at the Earth. The Earth’s climate response to these prolonged low solar radiation inputs involves heat transfer to the deep ocean causing a time lag longer than a decade. The spatial pattern of the climate response, which allows distinguishing the CGC forcing from other climate forcings, is dominated by the Pacific North American pattern (PNA). The CGC minima, sometimes coincidently in combination with volcanic forcing, are associated with severe weather extremes. Thus the 19th century CGC minimum, coexisted with volcanic eruptions, led to especially cold conditions in United States, Canada and Western Europe.